More than 25,000 plants were sold over two days raising £5,500 for important conservation work on the chalk Downs around Dover.
The Plant Fair, which attracted around 4,000 enthusiastic gardeners, featured a water saving garden designed to beat drought conditions.
National Trust Property Operations Manager Virginia Portman said that flourishing flower and vegetable gardens could be maintained over the summer while reducing the use of water from the tap.
She said: "We have to make sure that we do not take too much water from the environment for our own use. Habitats can be seriously damaged by the over abstraction of water and by using water carefully in the garden we can help minimise environmental impacts."
The Fair was organised and run by National Trust volunteers, who raised all the plants and ran the stalls.
Virginia Portman added: "As usual our volunteers did a fantastic job and the Fair was yet again a tremendous success. A great amount of hard work goes into the preparations and we would like to thank everyone for their excellent work."
Veolia Water sponsors the Plant Fair and Water Efficiency Manager Ian McAthy said that there had been a good response to appeals to save water in the garden.
He said: "Gardeners realise that we have to protect the environment and the use of water butts is now very widespread. Water saving in the garden helps bring down demand and allows us to reduce the amount of water we abstract from local sources on the chalk Downs and from gravel beds on Romney Marsh.
"After two dry winters in the south east we need to save all the water we can as unfortunately spring and summer rain is mostly taken up by natural environment or lost through evaporation. We need to be prudent in our use of water now in case there is a third dry winter."
The National Trust will soon be planning the next annual Plant Fair alongside other fund raising activities and is hoping to recruit additional local volunteers.For more details contact Gareth Wiltshire, Visitor Experience Manager, on 01304 207326.